JP2021021746A - Method for diagnosing and evaluating structure based on always fine movement of structure - Google Patents

Abstract

To provide a method for diagnosing and evaluating a structure based on the always fine movement of the structure, which is different from a conventional method in which soundness and safety of the structure is achieved by directly applying an external force or the like to an object, and earthquake resistance and soundness of the structure and the effect of a countermeasure work and a reinforcing work can be inexpensively and quickly diagnosed and evaluated.SOLUTION: Disclosed is a method for evaluating performance of a structure by the always fine observation, which includes the steps of: constantly observing a fine observation history at the same time at a plurality of observation points in the structure; calculating an estimated value of an index used for an earthquake resistant design of the structure using the root mean square (RMS) of these time histories; and performing evaluation of the earthquake resisting performance based on the observation of the structure using a ratio to a value of the index used at a point of time when this value is designed.SELECTED DRAWING: Figure 4

Description

The present invention is a technique relating to a diagnostic evaluation method for a structure, which diagnoses and evaluates the seismic resistance and soundness of the structure and the effects of countermeasures and reinforcements based on the constant tremor of the structure.

Diagnosis and evaluation of the performance of various objects around us, from human bodies, machines, buildings, etc. to cliffs, ground, trees, etc., is the basis for living a safe and comfortable life, and many Equipment and technology have already been put into practical use. Among these, there are the following difficulties in diagnosing and evaluating the seismic resistance and soundness of structures such as buildings and infrastructure facilities: they are exposed to various natural environmental conditions for a long period of time. Each one has a different shape and material. Destruction test is not possible. The size exceeds the scale of a person. It is difficult to move. It cannot be completely described in documents or data. The structure is supported by the ground, and the properties of the ground are more complex than those of man-made structures visible on the ground. There is a high degree of uncertainty regarding the timing, scale, and vibration characteristics of sudden external forces such as earthquakes.

In addition, the method of calculating the structural seismic index (Is value) has been conventionally used for the seismic resistance evaluation of existing buildings, but it is complicated because an expert judges information such as drawings and inputs it into a computer program. It took a lot of money and time to perform various calculations. Furthermore, since the calculation method is not unique and there are inputs based on branching and judgment, it is said that subjective elements are likely to be included as a result, and judgment meetings by third-party organizations have been institutionalized. .. That is, the above-mentioned conventional method requires a large amount of cost, labor, and time.

Diagnostic evaluation methods for the entire structure that have been put into practical use so far include a) checking the consistency with drawings and calculation sheets, b) re-doing structural calculations, and c) another calculation method. There are those that are recalculated in, d) that vibrates and measures the way of shaking with a vibrator, e) that scores are added in a check sheet format, and f) that is based on microtremor observation. Inspection at the time of new construction belongs to a) or b), and seismic diagnosis belongs to c). However, since the method using the calculations listed in a) to c) picks up the numerical values that are the basis for it from the drawings, etc., it is assumed that the actual structure and support conditions are the same. Become. Further, even if the inside of the structure can be calculated in detail and 100% accurate judgment can be made, the calculation result is almost influenced by the conditions of the foundation and the surrounding ground. Also, in the method using the exciter shown in d), the energy of the exciter is too small compared to the potential energy of the structure and the surrounding ground, and it is judged with high accuracy as in the case of structural calculation. Is hard to say.

Constant tremors contain much more comprehensive, detailed and abundant information on structures and surrounding ground than the information on which the above methods are relied. The constant tremor has a small amplitude of about several microns, but it has a large amount of energy because the huge mass of the structure and the surrounding ground is constantly oscillating. In terms of space, it vibrates in all parts of the structure and the surrounding ground, and the amount of information is so large that it cannot be compared with the information of design documents and vibrators. In particular, in evaluating the risk of a large earthquake, it is important to be able to measure the actual vibration with the input source as the ground, as in the case of an earthquake.

Conventionally, some diagnostic methods for structures that always utilize fine movement have been tried, such as the disclosure technique of Patent Document 1.

Japanese Patent No. 3876247

However, the prior art is a method of visually determining the period that seems to be superior from the Fourier spectrum and discussing the change, and only extracts a small part of the abundant amount of information that the tremor always has. There wasn't. Therefore, the diagnostic results were inadequate in both accuracy and content, and could not establish a position as a diagnostic method for structures. In addition, the prior art including Patent Document 1 could not be applied to the evaluation and diagnosis within the framework of the current standard because the calculated index was not the index used in the current design standard or the seismic diagnosis standard. Moreover, none of the design indicators of the current standard directly evaluate the continuity of use of structures. However, the seismic design standards and seismic diagnostic standards for current structures are collectively referred to as the current standards in this specification. In addition, seismic diagnostic criteria are simply referred to as diagnostic criteria, and seismic design criteria are simply referred to as design criteria.

In addition, there was no method to actually measure the distribution coefficient in the height direction of the layer shear force used in the current seismic design, the retained horizontal strength, and the product of the cumulative strength index and the shape index used in the seismic diagnosis. .. The current standard does not specifically indicate the assumed ground motion, and there is also the problem that the current calculation method is not unique and has input based on branching and judgment.

In view of the above problems found in the prior art including Patent Document 1, the present invention uses the information of constant tremor for diagnosis and seismic repair design of existing existing structures, cumulative strength index and structural seismic index. The above indicators and damage are related to the expected value of, the expected value of the distribution coefficient of the layer shear force in the height direction used in the current new construction design, and the degree of damage for directly evaluating the continuity of use of the structure. The purpose is to provide a new method for extracting information on existing structures and surrounding ground systems and using them for structure design and diagnostic evaluation by directly acquiring the estimated values of degrees from the measured values of microtremors. And. The method of the present invention is referred to as Micro Tremor Diagnosis (MTD).

The present invention has been made to solve the above-mentioned problems, and its structural feature is that in a method of evaluating the performance of a structure by constant microtremor observation, at a plurality of observation points in the structure at the same time at all times. The tremor time history is observed, and the square mean square root (RMS) of these time histories is used to calculate the estimated value of the index used for seismic design of the structure, and the index used at the time of designing this value is calculated. The purpose is to evaluate seismic performance based on the observation of the structure using the ratio to the value.

Further, the continuous fine movement time history measured continuously is divided, a plurality of partial time histories are extracted, the expected value of the index is calculated for each partial time history, and the sample average is used as the estimated value of the index. be able to. In this case, the duration of the partial time history is preferably 1 to 2 minutes.

In the present invention, the observations are performed after the new construction of the structure, before and after the repair work, and at the time of periodic diagnosis, and the estimated values at each observation time are compared with each other to obtain the seismic performance of the structure and a large earthquake. It may be used to diagnose and evaluate at least one of the risk of collapse at the time, the change over time in the continuity of use, and the change before and after the repair work.

In the present invention, the index can be the distribution coefficient of the layer shear force in the height direction specified in the current standard or the retained horizontal strength specified in the current standard.

Further, in the present invention, the index may be a base shear coefficient specified in the current standard or an acceleration response magnification specified in the current standard.

Further, in the present invention, the index may be the product of the cumulative strength index and the shape index defined in the current standard, or the degree of damage or the degree of fall risk newly defined in the present invention.

According to the present invention, the cumulative strength index used for diagnosis and seismic repair design of existing existing structures, the expected value of structural seismic index, and the height direction of the layer shear force used in the current new construction design. Vertical arrays are provided for each part of the structure by directly obtaining the expected value of the distribution coefficient and the estimated value of the degree of damage newly defined to directly evaluate the continuity of use of the structure from the measured values of tremors. As a result of being able to measure the vibrational sentiment, strength, degree of damage, etc. of each floor part (zone) by the provided observation, seismic resistance, soundness, or repair design is far more detailed, quicker, and cheaper than the conventional method. It was possible to evaluate the effect of.

That is, according to the present invention, by using the above indicators, diagnostic evaluation or evaluation can be performed much cheaper and faster than the current diagnostic evaluation or inspection method after new construction, after repair work, and at the time of regular diagnosis. Since inspections can be performed, rational seismic retrofitting design and seismic design of new structures can be performed.

The explanatory view which shows the structural example of the diagnostic system to which the method of this invention is applied. The flowchart which shows the basic processing procedure performed between a microtremor and an analyzer. Explanatory drawing which shows the factor necessary for calculating structural seismic index, holding horizontal strength and damage degree in the method of this invention. The flowchart which shows the procedure of the whole processing of the method of this invention. An explanatory diagram showing the contents of processing performed in the analyzer for each routine. It is a schematic diagram showing the action and seismic force of an actual earthquake, of which (a) shows the actual action, (b) shows the spring / mass system, and (c) shows the seismic force. FIG. 6 (b) is a model (single point system) in which a plurality of mass points and springs drawn by black dots and lines are combined into one. A graph showing the bilinear type cumulative strength index and interlayer deformation angle relationship. The graph which shows the relationship between the friction type interlayer shear force and the acceleration of a support part. The graph which shows the relationship between the friction type interlayer shear force and the interlayer velocity. The graph which shows the friction type interlayer shearing force and interlayer displacement relation. A layout plan of four types of microtremors on the first floor, taking a four-story hospital as an example. The layout of four types of microtremors on the second floor, taking the same four-story hospital as an example. A layout plan of four types of microtremors on the third floor, taking the same four-story hospital as an example. A layout plan of four types of microtremors on the fourth floor, taking the same four-story hospital as an example. Y Hospital 1st floor pillar wall 2nd floor beam plan. Y hospital 2nd floor pillar wall 3rd floor floor beam plan. Y hospital X direction 1 axis assembly diagram. Y hospital X direction 2 axis assembly diagram. Y hospital X direction 4 axis assembly diagram. Y hospital Y direction A grid assembly diagram. Y hospital Y direction B grid assembly diagram. A panoramic view of the building for Example 2. The installation status of the A2 measuring instrument on the first floor in Fig. 23 corresponds to that in Fig. 25. Explanatory drawing which shows the measuring instrument arrangement and reinforcement position in correspondence with FIG. Fine movement displacement locus diagram of each floor. Animation of vibration on the roof of an 11-story SRC building measured before reinforcement. Animation of vibration on the roof of an 11-story SRC building measured after reinforcement. The figure which shows the moment of the movement of the roof surface after reinforcement by inputting the displacement data (XYZ3 component) by the fine motion meters installed at three places on the roof surface into the structural analysis result visualization software and visualizing (animating) it. A schematic diagram showing the arrangement relationship between a block wall, a foundation, and the ground and a fine movement meter. Explanatory drawing which shows the whole view of a block wall as (a)-(c) according to a situation. The layout of the fine movement meter on the block wall and the reference point.

The ground around the structure is constantly generating minute vibrations. The sources of vibration energy are tides, traffic vibrations, and the like. The amplitude is about several microns [10 = ^-6 m]. The constant tremor observed at a certain point of the structure (hereinafter, also simply referred to as "tremor") is amplified or attenuated while the tremor of the surrounding ground enters the structure from the foundation and propagates inside the structure. It is the result of

Constant tremors are observed with a tremor meter (accelerometer) installed in the structure. This is the absolute acceleration of a specific point in the structure, and is usually measured separately for the vertical component and the three orthogonal components in the two horizontal directions. Due to its small amplitude and short duration, the structure is a stationary linear system and constant tremors can be mathematically treated as part of a stationary stochastic process.

Hereinafter, examples of embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a configuration example of a diagnostic system to which the method of the present invention is applied. According to the figure, the entire diagnostic system consists of a microtremor 1 arranged on the layer boundary surfaces 10a, 10b, 10c of each layer of the structure 10 and various vibration characteristic indexes based on the data recorded by the microtremor 1. , And an analyzer (for example, a personal computer) 2 that calculates various seismic resistance evaluation indexes and new evaluation indexes used in the current standard.

Of these, the microtremor (for example, the microtremor JU410 manufactured by Hakusan Kogyo) 1 has a built-in acceleration sensor, memory, and GPS. Further, the analyzer 2 is equipped with microtremor diagnosis software, receives the data recorded by the microtremor 1 via USB, LAN, or the Internet, calculates the method of the present invention described in detail below, and performs various vibrations. Calculate the characteristic index, various seismic resistance evaluation indexes used in the current standard, and new evaluation indexes. Further, in the analyzer 2, for example, the fine movement displacement data acquired by the fine movement meter 1 installed at three locations on a certain layer is sent to the visualization software mounted on the analyzer 2 to animate the movement of the surface in three dimensions. Above, it is visualized by displaying it on a display means (display) (not shown) provided in the analyzer 2 so that the vibration mode of the structure 10 can be visually confirmed at a glance. ..

Hereinafter, the outline of the method of the present invention will be described with reference to FIGS. 2 to 5. FIG. 2 is a flowchart showing a basic processing procedure performed between the microtremor 1 and the analyzer 2. According to the figure, the vibrometer 1 constantly measures and records tremors (acceleration time history of observation points and reference points on the layer boundary). The analyzer 2 filters the received measurement record data in the frequency domain, and then acquires the acceleration time history of the frequency band near the natural frequency of the target structure. After acquiring the acceleration time history, it is divided into parts of about 2 minutes in the time domain, and the attention time history, the energy transfer coefficient, and various indexes are calculated for each part. After the calculation, the average value and standard deviation of the vibration characteristic index, seismic performance index, and seismic performance index for each part are calculated, and the average value is used as the estimated value of each index.

Further, according to FIG. 3, the magnitude of the assumed ground motion in the method of the present invention is represented by the maximum acceleration, the maximum velocity, the maximum displacement, and the strong motion duration. In addition, the microtremor is installed in a vertical array on each layer and reference plane of the target structure. Furthermore, the performance of the target layer of the target structure is expressed by the required horizontal strength, toughness index, aging index, and limit number of repetitions. After the installation of the microtremor is completed, the microtremor measurement using the microtremor 1 and the measurement result analysis using the analyzer 2 are performed according to the processing procedure shown in FIG. 2, and the vibration characteristic index (central period, layer) is analyzed. Calculate the seismic performance evaluation index (coefficient that shows the distribution of shear force in the height direction), seismic performance evaluation index (possessed horizontal strength, product of cumulative strength index at the end and shape index), and seismic resistance evaluation index (history absorption energy, damage degree) To do. After processing the above, the structural seismic index, the possessed horizontal strength ratio, and the degree of damage will be calculated and the processing will be completed.

FIG. 4 is a flowchart showing the procedure of the entire processing of the method of the present invention. According to the figure, first, a preliminary survey of the target structure is conducted. Specifically, we will collect literature materials such as design drawings, calculations, extension / renovation history, damage history, and past seismic diagnosis, and determine the position where the microtremor can be installed by on-site reconnaissance. Next, as a fine movement measurement plan, the measurement time zone, the measurement time, the arrangement of the fine movement meter (instrument), and the reference plane are determined. After formulating the fine movement measurement plan, the instrument absolute time adjustment, fine movement measurement, and data recording are performed as the fine movement measurement implementation, and the attention time history calculation, vibration characteristic index, and performance index calculation are performed as the analysis implementation. After completing the above, diagnosis is performed. In this case, the structural seismic index or the possessed horizontal strength ratio is used for diagnosis according to the current standards, and the degree of damage is used for seismic performance evaluation.

FIG. 5 is an explanatory diagram showing the processing contents performed in the analyzer 2 for each routine. According to the figure, the input data includes each data as assumed seismic motion specifications, observation tremor time history, observation time, observation frequency band, analysis time, analysis frequency band, and each data as observation point attribute. , Each data as a structure specification is input.

In the calculation routine, the attention fine movement time history is calculated, the part division is performed, the vibration characteristic index is calculated, and the performance index is calculated. As for the preliminary calculation routine, FFT, filter, zero point correction, root mean square calculation, central frequency calculation, and bandwidth exponent calculation are performed.

In the display routine, input data display, observation time history, spectrum, central frequency, bandwidth index display, vibration characteristic index display, performance index display, time history display, power spectrum display, locus display, and surface Motion animation display is also performed. The output / transfer routine is performed via paper, a hard device, USB, LAN, etc., radio waves, or the like.

The outline of the method of the present invention has been described above based on FIGS. 1 to 5, but the method of the present invention will be described in more detail below. In the method of the present invention (MTD: Micro Tremor Diagnosis), the root mean square (RMS), peak factor, zero cross period, central period, bandwidth index, and reference point for the duration, displacement, velocity, and acceleration time history of tremors. Quantitatively analyze the tremor and the vibration characteristics of the structure using the energy transfer rate between the tremor displacement, velocity, acceleration time history and the attention tremor time history. This is a characteristic grasp of a stochastic process using a second moment of area and a correlation analysis between input and output.

In the fine movement measurement, several sets of time history are extracted from the duration measured continuously for one fine movement meter arrangement, the following quantities are calculated for each set, and the sample average and standard deviation are calculated. Ask. For seismic resistance evaluation, the sample average of each quantity is used as an estimate of the expected value of each quantity.

FIG. 6 is a schematic diagram showing the action and seismic force of an actual earthquake, of which (a) shows the actual action, (b) shows a spring / mass meter, and (c) shows the seismic force. As shown in FIGS. 6A to 6C, the tremor diagnosis is calculated by modeling the surrounding ground 21 as a rigid floor and the structure 10 as a mass point and a spring. This is the same as the current seismic standard.

The ground is constantly vibrated with a minute amplitude of about several microns [ ^10-6 m] due to tides, traffic vibrations, and the like. This is called constant tremor (Micro Tremor). The same applies to the peripheral ground 21 of the structure 10 represented by the solid rectangle in FIG. 6A. Since the tremor enters the structure 10 from the foundation and propagates inside the structure 10, the structure 10 also constantly causes tremors. Since the random input is received for a sufficiently long period of time, it is considered that both the surrounding ground 21 and the structure 10 are vibrating in a unique vibration mode.

By installing a plurality of microtremors (accelerometers) 1 in the structure 10 as shown in FIG. 1, the time history of microtremors can be observed. For example, one unit is installed in a vertical array at a representative point of each layer so as to correspond to modeling each layer of the structure 10 with mass points and springs as shown in FIG. 6 (b). Since the amplitude of the tremor is so small, the structure 10 is a stationary linear system in a finite duration, and the constant tremor can be mathematically treated as part of a stationary stochastic process. ..

Seismic motion is a phenomenon in which displacement due to the destruction of bedrock and ground in the source area becomes a wave that reaches the ground around the structure and vibrates it, so the source of vibration energy is different from constant tremor, but the amplitude is small. Then, since it is considered that the surrounding ground and the structure vibrate in the natural mode, it is considered that the vibration is always the same as the fine movement.
From the above, the following indexes are calculated by microtremor observation, the dynamic properties of the structure and the behavior at the time of an earthquake are predicted and calculated, and the current seismic performance evaluation index and the new evaluation index are calculated.

1. 1. Central period (vibration characteristic index 1)
The central period T _c [sec] of the tremor displacement in a certain direction at a certain point in the structure is calculated as follows.

However, ω _cy [rad / sec] is the central frequency calculated by dividing the RMS of the time history obtained by differentiating an arbitrary tremor time history by its own RMS (the "center" here is the English word "central frequency". Is used for "central" when translated into Japanese, and it does not mean that it is in the center of something, but it is the expected value of the zero cross frequency, and the frequency characteristics of the time history are discussed in the irregular vibration theory. It means the frequency that plays a central role in the above), and a (see column a in Table 1) and b (see column b in Table 1) are the displacement time history and the velocity time history, respectively. RMS.

Here, [0, t ₀ ] is the duration of the tremor time history. The central period can be similarly defined for the velocity, acceleration, rotation angle, and the like.
It is possible to calculate the central period of the time history obtained by multiple microtremors installed in a certain part of the structure and compare them with each other to determine whether the part is vibrating in its own vibration mode. it can.

2. 2. Expected value of coefficient representing the distribution of layer shear force in the height direction (vibration characteristic index 2)
According to the current seismic standards and diagnostic criteria for buildings, the seismic force ( _Pj ) acting on the jth layer of a building is the seismic intensity ( _kj ) and the seismic intensity ( _kj ) of that layer against the background of the mechanical model shown in Fig. 6 (b). It is expressed as the product of weights (w _j ).

From the above relationship, the maximum shear force generated in the i-th layer when a building consisting of n layers vibrates under the action of an earthquake is called the layer shear force a (see column a in Table 2), and that layer is weight support b is given as the product of the seismic story shear coefficient (b column see Table ₂₎ (C i).

Further, the seismic layer shear force coefficient (C _i ) is _divided into a regional coefficient (Z), a vibration characteristic coefficient (R _t ), a standard shear force coefficient (C ₀ ), and a coefficient (A) representing the distribution of the layer shear force in the height direction. It is specified as the product of _i ). It is stipulated that C ₀ = 0.2 should be used in the primary design assuming small and medium-sized earthquakes, and C ₀ = 1.0 should be used in the secondary design for large earthquakes.

Regarding the first layer,

From the above, _Ai is the value b (see column b in Table 3) in which the layer shear force is standardized by the shear force a in the first layer (see column a in Table 3) and the weight above that layer. It is derived that it is the ratio of α _i to the amount standardized by the total weight (total weight) W above the first layer.

Using the above equation, assuming that the absolute acceleration energy transfer rate a in the k direction of layer i obtained by the microtremor diagnosis (see column a in Table 4) is preserved even at the time of elastic response by seismic motion input. This results in the expected value b of the maximum value of the absolute acceleration (see b column in Table 4) was calculated by multiplying the maximum acceleration of the reference point, the layers of the mass m _j of this and the structure, expected maximum story shear The value c (see column c in Table 4) can be obtained, and the expected value E [A _ik ] of the coefficient representing the distribution of the layer shear force in the height direction of the layer i in the k direction can be obtained ( _Equation 9). However, the maximum acceleration of the reference point is not displayed because it comes to the denominator and child on the rightmost side of Equation 9 and is reduced. Further, the absolute acceleration energy transfer rate a (see column a in Table 4) is the energy transfer rate defined in paragraph “0067” of the present specification, in which the minute movement time history of interest is taken as the absolute acceleration time history, that is, , The ratio of the absolute acceleration time history in the first layer k direction to the RMS of the absolute acceleration time history in the first layer k direction. The second equal sign from the right of Equation 9 is derived from the equation of motion (see paragraphs "0032" to "0034") for the mechanical model of the structure of FIG. 6 (b). In addition, the last equal number of Equation 9 is based on the assumption described in paragraph "0021", that is, the absolute acceleration time history of each layer (layer i) obtained by constant tremor observation is a part of the stationary stochastic process. Based on the assumption that the expected value of the maximum value within a certain duration can be calculated by multiplying the RMS by the peak factor, the peak factor of the absolute acceleration time history of each layer can be calculated. Are equal to each other. As shown above, the method of the present invention obtains the design index of the current standard defined by using the maximum value of the force acting in the structure at the time of an earthquake by microtremor observation based on the above assumptions. It is estimated using the RMS of the absolute acceleration time history of each layer. In this method, an estimated value of the maximum value with less variation (stable), that is, an estimated value of the design index, is obtained as compared with the method using the actually measured maximum value.

By the way, in the seismic code, from various analyzes and examinations, A _i is defined with α _i (standardized weight) appearing in the above two equations and the primary natural period T of the building as parameters as follows.

However, T [sec] is the ratio of λ to the total height h [m] of the floors (excluding the basement) where most of the columns and beams of the building are made of wood or steel, using the following formula. It is supposed to be calculated.

The above regulation is devised so that the maximum response shear force distribution of each layer from the low layer to the super high layer can be expressed by one formula for a building which is a tower-like structure. In the seismic reference instead to calculating A _i in the above formula, directly for individual buildings, the maximum value of the story shear modeling to at time history analysis or the like method shown in FIG. 6 (b) it is also allowed to obtain the a _i to calculate.

3. 3. Expected values of average transmission rate and response magnification (vibration characteristic index 3)
When considering the action of an earthquake on the i-layer in the model of FIG. 6 (b), the RMS or maximum value of the average acceleration, average velocity, etc. of the portion b (from the i-layer to the n-th layer) supported by the layer. It is convenient to use the following index that gives.

Here, mj is the mass of the jth layer, a (see column a in Table 5), and b (see column b in Table 5) are the energy transfer rates of the acceleration and velocity in the k direction of the jth layer, respectively. , _Baik is _referred to as average acceleration energy transfer rate, and B _vik is referred to as average velocity energy transfer rate. However, the energy transfer rate is the ratio of the RMS of the tremor time history of interest to the tremor time history of the reference point, and in the tremor diagnosis, it is assumed that this is preserved at the time of the maximum elastic response due to the seismic motion input, and the peak factor is assumed as appropriate. Then, the maximum response of the time history of interest is calculated by multiplying the maximum input value of the reference point by the energy transfer rate.

For example, using the above average acceleration energy transfer rate, the k-direction component of the spatial average value of the absolute acceleration time history a _k (t) of each point (mass dM) of the portion b supported by a certain layer i in the structure. the a _k expectation E [sigma _Ak] of the RMS (t), can be calculated as follows according to the acceleration time history of the reference point a (see Table 6).

The following relation between the average acceleration energy transmission factor B _aik defined expectation A _imk and formulas 13 coefficients representing the vertical direction of the distribution of story shear equation 9.

That, A _imk can be said to mean acceleration and a first layer portion target portion i to support is a ratio of the average acceleration of the portion supporting (whole structure).
In Equation 13, the average acceleration transmission rate _Baik with j = 1 is the average absolute acceleration a of the structure (see column a in Table 7) and the absolute acceleration b at the reference point (see column b in Table 7). The ratio, that is, the expected value of the acceleration response magnification _Ramk when the entire structure is reduced to a one-degree-of-freedom system as shown in FIG.

Similarly, B _v1k in which j = 1 in Equation 14 can be said to be the expected value of the velocity response magnification when the entire structure is reduced to a one-degree-of-freedom system.

It is assumed that the current standard uses the standard shear force coefficient of Equation 6 as C ₀ = 0.2 in the primary design assuming small and medium-sized earthquakes and C ₀ = 1.0 in the secondary design for large earthquakes. This is because the maximum acceleration of the seismic motion is 0.07G to 0.08G for small and medium-sized earthquakes and 0.33 to 0.4G for large earthquakes, and the acceleration response magnification of short-period buildings is considered to be 2.5 to 3. It is said that.

4. Expected value of possessed horizontal strength (seismic performance index 1)
The seismic criteria, the layers of the structural model of the building is gradually increased shear forces A _i distributed loading by, a column of the i layer shear forces acting on the layer a (Table 8 when the i-th layer to yield (See) is defined as the holding horizontal bearing capacity b (see column b in Table 8).
The relationship between the layer shear force generated in the structure due to the fine movement of the ground and the acceleration of the reference point can be expressed by the average acceleration transmission rate ( _Baik ) defined in paragraphs "0064" to "0080" of the present specification. Further, the relationship between the interlayer displacement and the acceleration of the reference point can be expressed by using the transmission coefficient defined in paragraph “0067” of the present specification. Using these, the expected value of the layer shear force when the maximum value of the interlayer displacement of the i-th layer reaches the yield displacement when the structure responds linearly can be calculated. It can be considered that this is the expected value c of the retained horizontal strength (see column c in Table 8) assuming that only the layer i does not yield.
The energy transfer coefficient e (see column e in Table 8) of the inter-story displacement (e _ik (t)) in the layer i k direction with respect to the acceleration d in the k direction of the reference point (see column d in Table 8) is determined by each RMS. The ratio of is defined as follows.

If the maximum value of the acceleration of the reference point when the maximum value of the inter- _story displacement e _ikmax reaches the yield displacement e _ikY is set to a _ikY ,

The expected value a of the maximum value of the layer shear force at this time (see column a in Table 9) is the mass b of the portion b supported by the i-th layer (see column b in Table 9), and the maximum average acceleration of this portion. It can be calculated by multiplying the expected value A _bkmax .

The maximum acceleration of the reference point and the expected value of the maximum value of the average acceleration of the above-mentioned part b are related by using the average acceleration energy transfer coefficient _Baik .

From the above,

From Formula 21 and Formula 24,

The expected value of the layer shear force coefficient when reaching the retained horizontal strength, _Cuikm, is obtained by dividing the above equation by the weight supported by the layer using the relation of Equation 5.

However, the floor height of the i-th layer in the k direction is H 0 _ik [m], the yield deformation angle is R _{Yik RY} [rad], and g [m / sec ² ] is the gravitational acceleration. Also, the expected value of Shear force coefficient of the first layer when reaching the holdings lateral strength, i.e., expected values C _Ui1km the base shear coefficient is calculated by dividing the relation equation 8, the above equation in A _i .. It can be seen that this can be expressed by the acceleration response magnification _Ramk and the energy transfer coefficient a (see Table 10) of the inter- _story displacement with respect to the acceleration of the reference point using the equations 9, 17 and 19.

The possessed horizontal strength ratio is calculated by dividing the expected value of the possessed horizontal strength obtained above by the required retained horizontal strength specified by the earthquake resistance standard.

5. Expected value of the product of cumulative strength index and shape index at the end and structural seismic index (seismic performance index 2)
The seismic criteria for each Harima and column bound direction of each floor of the middle low-rise RC system building (layers) (two horizontal directions), the structural seismic index I _s, possess performance basic index E ₀ and the shape index S _{D and,} It is expressed as the product of the aging index T.

Regarding the holding performance basic index E _{0 in the} above formula, a detailed formula is specified to calculate by aggregating the product of the strength index (C) and the toughness index (F) in each direction of each column, wall, and beam of each layer. There is. However, in principle, it is explained that the possession performance basic index E ₀ is the product of the strength index and the toughness index of the layer (E ₀ = C × F). The toughness index layer, since the layer is a toughness index corresponding to each layer deformation reaches ultimate limit, which represents a F _U, accordingly, base shear coefficient at story drift the layer reaches the ultimate limit The coefficient equivalent to (the cumulative intensity index at the end) is expressed as _CTU .

From the above relationship

Equation 29 is derived on the assumption that the layer shear force a (see column a in Table 11) is bilinear with respect to the interlayer displacement e, as in the line segment OYU drawn in FIG. In this case, the layer shear force (cumulative strength index) at the yield point Y and the final point U is equal (C _TY = C _TU ), which is a cumulative strength index for the yield correlation displacement (e _Y ). However, Figure 8 is a cumulative strength indicator C _T by dividing the story shear a (see a column of Table 11) in the height direction of the distribution coefficients A _i of the weight Σw and layer shear forces the layer support, The inter-story displacement e is divided by the floor height H ₀ and drawn as the inter-story deformation angle R. The subscript i is omitted.

It is assumed that the inter-story displacement / layer shear force relationship obtained by the microtremor diagnosis represents the relationship shown in FIG. 8 although it is near the origin of the relationship shown in FIG. The seismic criteria, when the aging index T and toughness index F _U and 1.0, earthquake motion the reference is assumed (reference ground motion: G0) with respect, if the layer reaches the ultimate, I of the layer It is specified that the _S value is 0.6. Therefore, when the expected value (E [e _G0 ]) of the correlated displacement is calculated by multiplying the correlated displacement energy transfer rate _hegi obtained by the microtremor diagnosis by the reference point displacement corresponding to the reference ground motion (G0), this is If the yield displacement (e _Y = _RY H ₀ ), it can be said that the value is 0.6. Therefore, if _F U = 1, T = 1 in the formula 30,

Since the cumulative strength indicator and story drift (interlayer displacement) is assumed proportional to the expected amount multiplied by the k direction of the shape indicators ultimate when cumulative strength indicator of the i layer ((C TU _{S D) ik)} The value is calculated by multiplying the correlated displacement energy transfer rate h _egik obtained by the tremor diagnosis by the reference point displacement x _G0 [1978] corresponding to the reference seismic motion (G0) to calculate the correlated displacement (e _{G0 ik} ). It is the value obtained by multiplying the value obtained by dividing the displacement (e _Yik ) by 0.6.

Well, according to the seismic diagnostic criteria, the numerical value of I s ₌ 0.6, the 1968 Tokachi-oki earthquake, the estimated value of I _s value distribution of building a group that received a medium fracture or more of damage caused by the 1978 earthquake off the coast of Miyagi Prefecture and from a comparison of I _s value distribution for buildings of earthquake damage inexperienced, it is that with its validity has been verified. In addition, the 1978 Izu-Oshima near sea earthquake, the 1987 Chiba prefecture east offshore earthquake, the 2011 Great East Japan Earthquake, etc. are posted, but the observed ground motions up to the 1978 Miyagi prefecture offshore earthquake and the 2011 eastern Japan Since the maximum acceleration, speed, duration, etc. of the observed earthquake motions in the 21st century represented by the Great Earthquake are orders of magnitude, the earthquake motions assumed by the diagnostic criteria are those up to 1978 when the criteria were first established. I want to think.

The records of strong earthquakes observed by 1978 in Japan are published in a database by the US National Oceanic and Atmospheric Administration (NOAA). From the results of statistical analysis of this, it is considered that about 2.5 cm is appropriate as the expected value of the maximum displacement of the seismic motion at that time in both horizontal directions, and it is substituted into Equation 32. Further, the yield displacement e _Y [m] of the i-th layer of the same equation in the k direction is expressed by the floor height H ₀ [m] and the yield deformation angle _RY [rad], and is the cumulative strength index at the end from the energy transfer rate. Obtain an equation to calculate the expected value of the product of and the shape index.

From Equation 30 and the above equation, it is possible to calculate the structural seismic index I _s microtremors diagnosis.

However, structural seismic index I _sm is obtained from fine movement diagnosis, F _U, and T is the ultimate toughness index and aging indicators.

6. History absorption energy (seismic collection performance index 1)
Non-linear response calculation, that is, after a layer of the structure reaches the yield strength, that is, after exhibiting non-linearity with respect to stress, a design document describes how the structure deforms and moves under the influence of an earthquake. It is not easy to calculate from the information described in or to be described in, even if the seismic motion is specified and the structure and the ground are simplified as shown in FIG. 6 (b) or FIG.

A wide variety of models (constituent rules) regarding stress and strain acting between each layer of a structure after yielding are considered. Concrete and soil exhibit non-linearity even with very small strain. Further, as variables explaining the non-linearity, not only the interlayer displacement as shown in FIG. 8, but also its relative velocity, absolute acceleration, stress degree in other directions such as axial force, strain, and the like can be considered. ing. The members that make up the layer, the materials that make up the layers, and the connection status of each member are diverse, and there are also various methods for reducing them to a single constitutive law. Which is not the correct answer.

In seismic design, there are several typical non-linear models, which are used for analysis of experimental results at the member level or full-scale model, but they are suitable for the method of applying force and the method of measuring displacement, etc. of the experimental equipment. Even so, the effectiveness of actual seismic effects in three-dimensional space cannot be verified.

FIG. 9 shows the friction-type interlayer shear force / support partial acceleration relationship, FIG. 10 shows the friction-type interlayer shear force / interlayer velocity relationship, and FIG. 11 shows the friction-type interlayer shear force / interlayer displacement relationship. By the microtremor diagnosis, the vibration of the representative point of each layer of the actual structure can be measured, and the response characteristic of each layer to the structural model of FIG. 6B can be quantified. From the result, the expected value of the historical absorption energy using the friction type model as shown in FIGS. 9 to 11 can be calculated.

This model is a model of stress of a structure in which stones are piled up, and as shown in FIGS. 9 and 10, the absolute acceleration of the portion supporting the layer exceeds the limit acceleration, and a relative velocity is generated between the layers. Then, a constant shearing force acts in the opposite direction to the speed.

Starting from zero interlayer displacement, the interlayer displacement increases in a certain direction, and when it reaches a certain size, the structure is deformed so that the interlayer displacement continues to decrease, and it decreases to a certain size. Is shown in FIG. 11 when the relationship with the interlayer displacement when the structure is deformed so as to increase is drawn. Even in the bilinear type shear force / interlayer displacement relationship shown in FIG. 8, the relationship between the interlayer shear force and the supporting partial acceleration is shown in FIG. Therefore, the above friction type model can be applied to a portion of the bilinear type shear force / interlayer displacement relationship in which the shear force is constant (line segment YU in FIG. 8).

The historical absorption energy _Wik of the i-th layer calculated from the k-direction component is that the upper surface of the i-th layer of the structure causes a relative motion (interlayer displacement e _ik ) with respect to the lower surface as shown in the following equation. The restoring force (layer shearing force) a (see column a in Table 12) is the work _wick , and the increment (see column b in Table 12) is obtained by integrating the duration of vibration t ₀ .

Assuming that the spatial average absolute acceleration and mass of the part supported by the i-th layer in the k direction are A _ik (t) and (Σm), respectively, the equation of motion of the part supported by the part of interest in the k direction is as follows. become that way.

Since the restoring force is assumed to have a yield limit strength a (see Table 13), it can be seen from Equation 36 that A _ik (t) also has a limit value, and this is _defined as the limit acceleration A _chic .

From the tremor observation, the spatial average acceleration of the part supported by the i-th layer when the structure responds elastically, that is, when the restoring force does not have a limit value can be predicted, so this is referred to as a (see Table 14). To do.

Per unit mass when the restoring force is frictional and the bottom surface of the layer vibrates at acceleration a (see Table 14) and a (see Table 14) is part of a steady Gaussian process with a duration of s _0. The theoretical formula that expresses the expected value of the historical absorbed energy W _ik by each parameter obtained from the power spectrum density function of a (see Table 14) and the critical acceleration A _ci is obtained from the irregular vibration theory.

here,
E [*]: Expected value of * [operator]

Regarding the k direction of layer i a (see Table 15): Restoring force [N]
e _ik (t): Relative displacement between top and bottom [m]
A _chic : Limit acceleration [m / sec ² ]
Σw: Supporting weight [N]

Further, regarding the spatial average elastic response acceleration time history a (see Table 14) of the portion supported by the i-th layer at the time of an earthquake, and the k-direction component of the velocity time history obtained by integrating this:
s ₀ : Strong motion duration [sec]
T _vik : Central period of velocity time history [sec]
σ _aik : RMS of acceleration time history [m / sec ² ]
α _vik : Bandwidth index of velocity time history [dimensionless]
σ _vik : RMS of velocity time history [m / sec]

However, the strong motion duration s ₀ is a stationary Gaussian process (G (t)) having the same power spectral density function as the time history (x (t)) of the duration t ₀ having non-stationarity like seismic motion. It is a duration to be treated as a part of the duration s ₀ of, and the maximum value of x (t) is made to appear once on average as the maximum value during the duration s ₀ of G (t). is there.

The parameters below T _vik are calculated from the predicted values of the time history and energy transfer coefficient obtained by microtremor observation and the maximum value of the vibration time history of the reference point due to the assumed earthquake. First, assuming that the structure vibrates in the vibration mode obtained by microtremor observation even during an earthquake or during an elastic response, the vibration period T _vik and bandwidth index α _vik of a (see column a in Table 16) are The calculation is performed using the lower surface of the portion supported by the i-layer, that is, the tremor acceleration time history b (see column b of Table 16) on the upper surface of the i-layer. Further, regarding the RMSσ _vik of c (see column c of Table 16) and the RMSσ _vik of this velocity time history, the average transmission rate of each layer (j = i ... n) (paragraphs "0059" to "0075" in the present specification). (See) and the RMS of the reference point at the time of the earthquake.

The RMS of the acceleration and velocity at the reference point during an earthquake can be rewritten in relation to the expected value V _maxk of the maximum velocity at the time of the reference point and the expected value A _maxk of the maximum acceleration by using the peak factor.

Further, as for the critical acceleration in the k-direction of the i-th layer, the retained horizontal strength a (see column a in Table 17) obtained in paragraphs “0081” to “0100” of the present specification is the yield layer shear force (a (Table 17). Calculate using the same as (see column b)). From Formula 37 and Formula 25

From the above, the expected value W _mik [Nm] of the historical absorption energy of the i-th layer due to the large earthquake calculated from the k-direction component can be calculated as follows.

However, the yield displacement e _ikY is _expressed by the product of the yield deformation angle and the floor height. Also, regarding the layer i k direction,
R _Yik : Yield deformation angle [dimensionless]
H _0ik : Standard floor height [m]
a (see Table 18): Interlayer displacement energy transfer coefficient with respect to reference point acceleration [dimensionless]

In addition, regarding the k-direction component of the fine movement time history on the upper surface of the attention portion,
T _vik : Central period of fine movement speed time history [sec]
α _vik : Bandwidth index of tremor velocity time history [dimensionless]
However, the bandwidth index is the central frequency of the time history divided by the central frequency of the differential time history, and the bandwidth index of the fine movement speed time history is the central frequency and fine movement acceleration of the fine movement speed time history. It is the ratio of the central frequency of the time history.

Also, regarding the part supported by the layer
Σm: mass [kg]
B _aik : Average acceleration transmission rate (see Equation 13) [Dimensionless]
B _vik : Average speed transfer coefficient (see Equation 14) [Dimensionless]

Further, regarding the k-direction component of the large seismic motion of the reference point, the following parameters are given by the designer's judgment or the standard as determining the magnitude and nature of the input.
s ₀ : Strong motion duration [sec]
V _maxk : Maximum speed [m / sec]
A _maxk : Maximum acceleration [m / sec ² ]
γ _v : Peak factor of velocity time history [dimensionless]
γ _a : Peak factor of acceleration time history [dimensionless]

In addition, both sides of the above equation are divided by Σm / 2 to obtain a velocity conversion value V _mik [m / sec] of the expected value of the historical absorption energy per unit mass to be supported.

7. Degree of damage (seismic performance index 2)
Assuming that the degree of damage caused by the action of an earthquake in a certain layer of a structure is proportional to the historical absorbed energy, the ratio to the limit value can be referred to as the degree of damage ( _Id ) and used as a design index.

Here, about the k direction of the i-layer:
I _dic : Damage degree [dimensionless]
W _mik : Expected value of historical absorption energy [Nm ² / sec ² ]
W _lik : Limit value of historical absorption energy [Nm ² / sec ² ]

The limit value W _lik of the historical absorption energy can be calculated by accumulating the respective limit values on the assumption that the restoring force of each member or member group is a bilinear type as shown in FIG.

However, the limit value is calculated assuming that the energy absorbed in one repetition is obtained by doubling the area of the projection of the line segment OYU on the horizontal axis in FIG. 8, and is calculated as _nkj times this energy. Here, with respect to the individual members j in the k direction of the i-layer, or the member group j:
n _kj : Limit number of iterations [dimensionless]
q _kj : Strength [N]
F _jk : Toughness index [dimensionless]
e _Yj : Yield displacement [m]
R _Yik : Yield deformation angle [rad]
H _0ik : _Floor height [m]

The expected value of the yield layer shear force (retained horizontal strength) in the i-th layer k direction is calculated in paragraphs "0081" to "0100" of the present specification. Therefore, if the toughness index of the layer and the limit number of repetitions are given, , The limit value of history absorbed energy can be calculated. Using Equation 25, the entire layer is grouped together in Equation 47.

However, in the i-layer k direction, N _ik : limit number of iterations [dimensionless]
a (see column a in Table 17): Expected value of yield layer shear force (holding horizontal strength) [N]
_Fuik : Toughness index [dimensionless]
Σm: Mass of supporting part [kg]

As the quotient of the expected value of the historical absorbed energy of the formula 44 and the limit value of the formula 48, the damage degree is calculated as follows.

The degree of damage I- _dik is the average acceleration transmission rate _Baik , average velocity transmission rate T- _vik , and reference point acceleration of the part that supports the vibration characteristics obtained from the fine motion observation of the ground system around the structure in the k-direction of the layer i. Interlayer displacement energy transfer rate a in the direction of layer i in the k direction (see Table 20), the central period T _vik of the velocity time history, and the bandwidth index α _vik , and the characteristics of the input seismic motion are expressed as strong motion duration s ₀ and maximum velocity. It is represented by V _maxk and maximum acceleration A _maxk and their peak factors γ _v and γ _a , respectively. Further, as the structure Itoguchimoto, the i layer k direction of the yield deformation angle _{R Yik,} and uses a standard floor height _{H 0Ik,} restore performance is represented by toughness index _{F uik} and limit number of repetitions _{N ik.}

8. Seismic diagnostic criteria, current criteria, and seismic motion levels in line with recent seismic environments In microtremor diagnosis (MTD2017), the vibration amplification characteristics of structures are quantified as sample averages of energy transfer coefficient from the observed microtremor time history. In addition, the vibration mode is visualized and the natural period and bandwidth are measured. In the seismic resistance evaluation, the maximum elastic response is estimated from the energy transfer rate by inputting the vibration caused by a large earthquake at the reference point provided on the first floor, basement floor, etc. of the structure, and the expected value of the structural seismic index is calculated. .. In addition, the historical absorption energy is estimated from the predicted values of the average acceleration and velocity of the part supported by the layer of interest or the part, and the degree of damage is calculated. The setting of the seismic motion level required above depends on the judgment of each designer, but it is effective to convert the assumed level such as the current standard into the fine motion diagnosis input value and display it.

Table 19 shows the diagnostic criteria, the standard ground motion levels (maximum acceleration, velocity, expected displacement (Amax, Vmax, Dmax)) and the expected duration of strong motion (S0) that are considered to be assumed by the current criteria. In addition, the seismic motion level seen from the recent observed seismic motion is shown as a reference at the bottom. The diagnostic criteria are estimated from the seismic motion observed in Japan by 1978 as mentioned above. In addition, the current standard is estimated from the story of the person concerned with the standard establishment and the shape of the notification spectrum (2015 edition of the structural technical standard manual for buildings pp488-490 published by the National Government Bulletin Sales Cooperative Association). The recent observed seismic motion is estimated from the strong motion observation records of the 2011 Tohoku region Pacific Ocean offshore earthquake and the 2016 Kumamoto earthquake, but statistical processing is not performed.
The level of seismic motion in the recent seismic environment is an order of magnitude higher than the level of the current standard, and there is no point in using it as an input seismic motion in the framework of the current standard based on the maximum elastic response and the framework of microtremor diagnosis. Seismic design for this level of seismic motion needs to be done in a radically different way from the current method.

Positioning of microtremor diagnosis Microtremor diagnosis plays the following roles in rational seismic design.

(1) Confirmation Diagnosis and additional measures Engineering structures implemented micromotion diagnosis after completion after completion, vibration mode, the vibration period _(T c), the layer shear force distribution factor _{(A im),} response ratio _{(R amk,} R _vmk ), cumulative strength index a (see Table 20), and damage degree ( _Idm ) are measured and compared with the design calculation to confirm the validity of the calculation and construction, and if necessary, take countermeasures. to add. In addition to calculating each of the above indicators for the entire structure, the vibration characteristics of that part can also be grasped by measuring the vertical array installed in that part.

(2) Periodic soundness diagnosis and repair Perform microtremor diagnosis on a regular basis, measure each index in the preceding paragraph, and repair if deterioration of the structure is observed. In addition, after the repair, a fine movement diagnosis is performed again to confirm the repair effect.

(3) Diagnosis and seismic retrofitting of existing structures We will carry out microtremor diagnosis on existing structures constructed according to the current standards or old seismic standards, and design and construct countermeasures as necessary. In addition, measurement and diagnosis will be performed before and after reinforcement to quantitatively confirm the reinforcement effect.

(4) Analysis of the relationship between earthquake damage and the vibration characteristics of the ground and structures We will analyze the relationship between the degree of damage and diagnostic indicators, taking as an example the case where a building that has undergone microtremor diagnosis is damaged by an earthquake. This will lead to revisions to diagnostic methods and standard values for each index.

1) Target facilities and measurement method RC hospital building (4th floor is S) with 1 basement floor, 4 floors above ground, and floor area of 838m ² (1 span in X direction, 3 span in Y direction) completed in 1972. The 1st floor 12 to the 4th floor 15 in the building (tentative name Y hospital) 11 are as shown in FIGS. 12 to 15, and the results of performing a tremor diagnosis on the RC building hospital building 11 will be introduced. Seismic diagnosis was carried out in April 2014, and a reinforcement plan with a value exceeding 0.6 was also drafted, but it was judged that construction while operating the hospital was impossible, and the purpose was to prevent collapse. , SRF method (vertical method using polyester fiber belt: see paragraph "0194" in this specification), "shaft bearing capacity reinforcement" to reinforce the main columns is constructed.

The tremor observation was carried out by arranging four tremors 21 in four types as shown in FIGS. 12 to 15. In the first time (measurement 1) and the second time (measurement 2), one place is installed in each of A2 streets and A4 streets of each layer from the first floor to the fourth floor in a vertical array shape. In measurement 3, it was installed at points A4 on the first floor and points A2, A4, and B1 on the second floor. In measurement 4, it was installed at points A4 on the first floor and points A2, A4, and B1 on the third floor.

The measurement takes about 2 hours, and the instrument is installed, continuously measured for 5 minutes, and the instrument is rearranged in sequence, and the measurement and withdrawal are performed by 4 types of instrument arrangement. Before the reinforcement work, the hospital is in operation from 15:00 to 18:00 on August 8, 2017. After reinforcement, it will be from 14:00 to 16:00 on September 22, 2017. The construction period for the reinforcement work is from July 20, 2017 to September 30, 2017, but as of August 8, the work has not been carried out due to advance preparation only. In addition, as of September 22, the skeleton work was completed and only a few finishes were left.

In the tremor diagnosis, the time history of the total recording length of 5 minutes observed at each point is divided into 5 to 7 parts that allow overlap with each other for about 1 minute each, and each index for each part is calculated. Then, the average value and the standard deviation were calculated for each measurement. This average value is shown in each of the tables below in Table 21. The above measurements were performed before (before) and after (after) the reinforcement work of the SRF method, respectively, and the effect of the reinforcement effect was observed.

With the microtremor, the acceleration time history was observed, and after using a 10 Hz high-cut filter and a 0.2 Hz low-cut filter (fourth-order Butterworth), the velocity and displacement were obtained by numerical integration by the linear acceleration method. 16 to 22 show a plan and a framework diagram of the target building. Expansion joints are installed on 4'street. Seismic diagnosis is divided into 1 to 4'and other types. The diagnostic results cited herein are the results for 1 to 4'various ways.

2) The performance index table 21, in comparison with _C TU _{S D} to the expected value of the cumulative strength indicator _{(C T} S _D) values before and after reinforcement _mik obtained from seismic diagnosis calculation shown in Equation 32. Measurement 1 indicates A2 vertical arrays, and measurement 2 indicates A4 vertical arrays. Table 22 shows a comparison between the rate of change before and after reinforcement and the calculated value. Tables 23 and 24 show a comparison between the value W _Koik obtained by the microtremor diagnosis before and after reinforcement, the value W _Koik obtained by calculation, and the rate of change and calculation before and after reinforcement for the standardized input energy. Also, Table 25 and Table 26, the degree of damage expected value _{(I d0m)} values and calculated values of the front and rear reinforcement (I _d) and reinforcement before and after a comparison of the calculation. The values in parentheses in Table 21 are values in consideration of the second type structural element. Further, the calculation of the degree of damage is calculated by the mathematical formula 47 from the strength and toughness of the member group obtained by calculating the limit value of the historical absorbed energy by the calculation of the seismic diagnosis, and the historical absorbed energy is calculated by an approximate formula (). See paragraph "0199" herein). Further, in the calculation of this example, in obtaining the critical acceleration used in the calculation of the historical absorption energy (see paragraph "0149" of the present specification), the product of the cumulative strength index and the shape index (see Equation 32), not the possessed horizontal strength. ) Is used.

Reinforcement work was carried out by a method (SRF method) that secures shear strength and axial strength by wrapping a high ductility material (belt) made of polyester fiber around the main columns on each floor from the 1st floor to the 3rd floor. .. The reinforcement design ensures that the verification ratio of all columns exceeds 1.0. The maximum value of the test ratio of the axial force during an earthquake on each floor is called the collapse risk value ( _If value), and is used as a design index for reinforcement for the purpose of preventing collapse. The _If values before and after reinforcement are listed in the two columns on the right side of Table 25. In the calculation, the axial yield strength of the column is the residual axial yield strength at the time of large deformation (F> 3.0), so that the RC column has zero before reinforcement and the collapse risk value _If is infinite.

When Table 21 see before and after reinforcing the right diagnosis calculation, the reinforcement work, but the cumulative strength indicator C _TU S _D is decreased except for the X direction on the first floor, which is pillar shape with wall or return panel, This is because the pillar was wound by cutting a slit in the attached pillar. However, C _TU S _D after reinforcement reflects the diagnosis result to the strength and toughness of the increase or decrease of the reinforced member before the reinforcement is substantially calculated value obtained by aggregating performing grouping again. The change in shape index _SD due to cutting the slit is not taken into consideration. The decrease in the strength index due to the reinforcement work is the result of considering that there is a margin in the strength in the Y direction in this reinforcement design, and aiming to secure the shaft strength and prevent collapse even if the strength is slightly reduced. .. Also, by the reinforcing as shown in Table 25 and Table 26, the degree of damage I _d is greatly decreased to 20% to 30% before the reinforcement, after reinforcement, the reference value of 1.0 for all floors and direction It is below the limit, indicating that the damage was within the permissible limit due to the reinforcement work.

Table 21 and let us compare the values before the reinforcement of the cumulative strength indicator C _TU expected value of S _D and the cumulative strength indicator obtained in fine motion diagnosis (C _T S _{D) mik} by the diagnostic calculation shown in Table 22. Regarding measurement 2, although the fine movement diagnosis value is about 40% lower on the 3rd floor, it can be seen that the values are almost the same as those on the other floors. On the other hand, in the measurement 1, the first floor is almost the same, but the fine movement diagnosis result is about 20% of the diagnostic calculation on the second floor and the third floor, which is a significantly small value. This is considered to reflect the following structural features around the measurement position. As shown in the frame diagram of FIG. 17, the measurement 1 (2 copies) X direction is a frame having almost no wall. In addition, the opening of one adjacent wall is large, and there is no wall in three. On the other hand, the measurement 2 (4) X direction is almost a wall frame, and so is the adjacent 4'frame. Measurement 1 (2, A) In the Y direction, there is no wall or the opening is large. On the other hand, in the measurement 2 (4, A) Y direction, there is an opening but a wall. This is also reflected in the shape index of seismic diagnosis. That is, the shape index S _D shown on the right side of Table 21 shows a small value of 0.63 on the second and third floors in the X direction. As a result of the uneven distribution of the walls in the X direction, the inter-story displacement in both the XY directions is large in the vicinity of the two.

Looking at the rate of change before and after the reinforcement of the table 22, in the measurement 1 (around 2 _copies), and substantially uniformly increased by about 2 percent of _(C T _{S D) mik.} This is because the column reinforcement by the SRF method shown in FIGS. 16 to 22 improves the vibration characteristics of the 1st to 3rd X-direction frames at the center of the column and the Y-direction A-frame near the 2nd column, and with respect to the reference ground motion. It can be said that this is the effect of reducing the inter-story displacement. On the other hand, in the measurement 2, of the change before and after the reinforcement is not observed almost _has been reduced _(C T _{S D) mik.} However, looking at the absolute values in Table 21, in measurement 2, after reinforcement, the values were about 0.5 to 0.6 on the 1st and 2nd floors and about 0.2 on the 3rd floor in both the X and Y directions. It has become. Similarly, in measurement 1, the first floor is about 0.6, the second and third floors are about 0.2. The above is considered to be the result of stable vibration characteristics as a result of reinforcing the main columns by the SRF method.

Looking at the comparison of the magnitudes of the values obtained by the diagnostic calculation and the fine movement measurement shown in Table 22, the calculation and the measurement are almost the same values for both measurements 1 and 2 on the first floor where the eccentricity is small. This is because the setting of the expected value of the maximum ground displacement of the ground motion assumed by the microtremor diagnosis method and the seismic diagnosis (see paragraphs "0113" to "0114" in this specification) was appropriate in this example. Can be said to indicate. Further, on the 2nd and 3rd floors with eccentricity, values that are significantly different between measurements 1 and 2 are measured, which is an example showing that the detailed characteristics of the structure can be grasped by the vertical array observation.

Looking at the standardized input energy W _{K0 ik} and the permissible limit value W _{l 0 ik} shown in Table 23, the standardized history absorption energy shown on _{page 112} of the 2015 SRF Construction Method Design and Construction Guideline (hereinafter referred to as “P112”) that scaled input energy.) the substantially formula of W _E, the influence of ground motion and the structure with respect to the input energy is in the giving as coefficients m _{E =} 5.0 of uniform, input energy before and after reinforcement and calculation unchanged It has become. On the other hand, in the present specification, as shown in Equation 49, since the formula reflects the influences of the strength of the structure, the response magnification, and the bandwidth of vibration, it changes before and after reinforcement. However, Table 23, by multiplying the A _i green book W _E, are displayed as the scaled value by a mass of supporting.

The absolute value of the standardized input energy is as large as 4 to 7 times the calculation in the X direction of measurement 1 before reinforcement, which is greatly affected by eccentricity, but the others are almost the same. It can be said that it is a value. Therefore, it can be said that this example shows that the fine motion diagnostic method and the set value of the seismic motion level corresponding to the current standard shown in Table 19 are also appropriate for the degree of damage.

Looking at the rate of change of the standardized input energy before and after reinforcement shown in Tables 23 and 24, the measurement 1 having a large influence of eccentricity uniformly decreases to about 60%. On the other hand, in measurement 2, it decreased significantly on the 1st and 2nd floors in the X direction, but increased in both directions on the 3rd floor. In particular, the rate of increase in the Y direction of measurement 2 is as large as about 7 times. These are direct, it reflects changes in the emerged has reinforcing longitudinal strength _{(C T} S _{D) mik} Table 22. That is, in this example, since the cumulative intensity index is used in the calculation of the critical acceleration of the standardized input energy, the result reflects the increase / decrease in the intensity. However, although the rate of increase in the Y direction is large, the absolute value itself is not large compared to the permissible value.

Let's look at the degree of damage shown in Tables 44 and 45. According to the calculation, before reinforcement, the reference value exceeds 1.0 in the X direction, but after reinforcement, it falls below both XY directions (damage is below the permissible value). According to the tremor diagnosis, it is below the reference value except for the X direction of measurement 1, which is affected by eccentricity. The 3rd floor Y direction of measurement 2 is 1.16, but it can be considered to be almost a reference value.

From the above, in the event of a major earthquake assumed by the current standards, the building may be damaged by vibration in the X direction in the vicinity of the two ways, but the other parts may be damaged. It can be said that there is a high possibility that it will fall within the permissible limit. Although not be determined by the fine movement diagnosis, since collapse risk value I _f shown in Table 44 is equal to or less than the reference value 1.0 after reinforcement, spared collapse even when subjected to ground motion greatly exceed current standards it is conceivable that.

3) Coefficient A _i representing the distribution of layer shear force in the height direction
Table 27, the expected value of the coefficient A _i representing the height direction of the distribution of story shear values before and after reinforcement (A _imk), by Equation 9, the absolute obtained by Microtremors acceleration energy transfer rate a ( Table 4 refer) and those calculated from the mass m _j of each layer of the structure, formula for current standards (shown in comparison with the values obtained from equation 10), the reinforcement before and after conversion and calculation in Table 29 And the actual measurement ratio are shown.

Let's look at the values before and after reinforcement of the measured values. In measurement 1, the change is only about 2% at the maximum in each floor and each direction. In measurement 2, the increase is 10% to 20% on the 3rd floor, but the change is 5% or less on the 2nd floor. Looking at the ratio between the calculation and the actual measurement, on the second floor, the measurement points and the presence or absence of reinforcement are almost the same. On the other hand, on the 3rd floor, before reinforcement, the actual measurement is about 10% smaller than the calculation for both measurement 1.2, and after reinforcement, in measurement 2, the actual measurement and the calculation match, or the measurement is about 10% larger in the Y direction. ing.

Looking at the absolute values of each of the above values, the actual measurement and the calculation are almost the same. This is a measurement method by microtremor measurement of the coefficient representing the distribution of the layer shear force in the height direction, and the seismic intensity uniform distribution, which is considered to be the maximum response layer shear force distribution of low-rise buildings by the current standard, was actually measured. It shows that. In addition, the change before and after the reinforcement of the 3rd floor and the comparison with the calculation show the effect of correcting the strength of the 3rd floor, which was particularly strong by the reinforcement work, to bring it closer to the 2nd floor or lower by cutting a slit. it is conceivable that.

Regarding the 3rd floor Y direction of measurement 2, the measured A _i (A _imk ) is considerably larger than the calculation because the structure is such that the vibration of this part is increased by cutting the slit. Is shown. This is measured values of intensity indices shown in Table 21 _{(C T} S _D) reduction of _mik (0.60 → 0.20), the increase in normalized input energy _{W K0ik} shown in Table 23 (5.4 → 37 It appears in .9) and the increase in the degree of damage I _d0ik shown in Table 25 (0.80 → 1.16). However, the risk of collapse is less than 1.0 on each floor in the same table because the pillars were wound up by the SRF method after cutting the slit. In addition, in the same table, it can be confirmed by microtremor observation that the degree of damage in the vicinity of measurement 2 was almost the standard value (1.0) or less on each floor. Further, in the vicinity of measurement 1, it is less than 1.0 in the Y direction. Regarding the fact that damage in the X direction of measurement 1 is predicted to some extent, it is effective to apply seismic coating to one wall by the SRF method to absorb vibration energy. This reinforcement was done for the purpose of preventing collapse, and from the standpoint of damage control, we would like to implement the above measures in future construction.

4) average acceleration, average speed transfer rate _{B aik, B vik}
The average acceleration and the average velocity transmission coefficient are calculated from the tremor observation results by the formulas 13 and 14, and the values before and after the reinforcement are compared and shown in Tables 30 and 31. These are the spatial average accelerations or speeds of the parts supported by layer i of the structure and the accelerations of the reference points, or the ratio of speeds. Therefore, the first-order value is the average response factor for the entire structure. Further, A _i is a value obtained by standardizing the value of each floor of the average acceleration energy transfer coefficient _Baik by the value of the first floor (see Equation 17).

This building is located on the type 2 ground, the natural period of the ground T _c = 0.6 sec, the building height h = 14.3 m, the height of the steel frame part is 2.95 m, and the floor is a steel structure. The ratio λ = 0.206 to the height h [m] of (excluding the basement), therefore, in the current standard formula (see Equation 12), the building natural period is T = h (0.02 + 0.01λ) = 0. Calculated as .32 sec. Therefore, from T <T _c , the vibration characteristic coefficient R _t = 1.0 is calculated, and it is concluded that the acceleration response magnification is 2.5 to 3.0, which is the standard value at the time of establishment of the current standard. ..

Based on the above, let's look at the measured response magnification, which is the value on the first floor. Acceleration and velocity are almost the same values. In measurement 1, 2.5 to 4.0 before reinforcement, 2.0 to 3.7 after reinforcement, and in measurement 2, 2 before reinforcement. .0 to 2.4, 1.6 to 2.2 after reinforcement. The absolute value is roughly equal to the assumption of the current standard of 2.5 to 3.0. This shows the validity of the tremor diagnostic method.

Next, let's look at the rate of change before and after reinforcement. As shown in Table 31, regarding the acceleration response magnification of the part supported by each floor, although only the Y direction of measurement 2 after reinforcement increased slightly (7%), 70% in each direction at other measurement points. It has decreased to about 90%. The speed response magnification increased slightly in the Y direction of measurement 2, but decreased in the others. These figures quantitatively indicate that the structural system has changed so that it is not easily affected by the earthquake due to the reinforcement work. These values are used in the calculation of the degree of damage, and the above-mentioned features appear in each index value described up to the previous section.

5) Fine movement characteristics Table 32 shows the RMS of the fine movement acceleration before and after reinforcement, and the energy transfer coefficient and the rate of change before and after reinforcement. Table 52 shows the central period and bandwidth index of the tremor acceleration before and after reinforcement. Similarly, Tables 34 to 37 show the characteristics of the fine movement speed and the displacement. The tremor acceleration is measured by an accelerometer, and the velocity and displacement are obtained by integrating the velocity and displacement by the linear acceleration method after processing the 10 Hz high cut and 0.2 Hz low cut filters. In each table, the floor is the floor of that floor.

The energy transfer rate is the ratio of the RMS of the reference point defined in paragraph "0067" of the present specification to the RMS of each floor, that is, the amplification factor of vibration, and is a factor for calculating each diagnostic index shown up to the previous section. It has become.

The central period is Formula 1 and the bandwidth index is calculated by the method described in paragraph "0156" herein. The central period is the expected value of the zero cross period in the case of a steady Gaussian process, and the bandwidth index is 1.0 for a sine wave and 0 for white noise. The larger the bandwidth, the closer to zero. Looking at the changes before and after reinforcement, the acceleration is almost the same or slightly larger before and after. Regarding the velocity, the central period is slightly larger in measurement 1 and slightly decreased in measurement 2. The bandwidth index is increasing at both stations. That is, the bandwidth is narrowed. Looking at the tremor displacement, the central period clearly decreases and the bandwidth increases after reinforcement. This indicates that the reinforcement brought the vibration closer to a sine wave and improved the rigidity of the structural system.

Tables 38 to 40 show the fine movement acceleration, velocity, and displacement in comparison with the measured values of the central period and the calculated values of the primary natural period of the current standard. Since a structure subject to tremor or seismic motion vibrates irregularly, the central period of displacement, velocity, and acceleration increases with bandwidth (see paragraph "0156" herein). In this example, there are central periods of acceleration, velocity, and displacement around the values of the primary natural period calculated by the current standard formula. As for acceleration, velocity, and displacement, values of substantially the same central period are obtained at each point, each floor, and each direction, so it is considered that the entire building vibrates in a unique mode.

1) Target facility and measurement method The measurement target is the 11-story SRC structure (2 spans in the X direction, 1 span in the Y direction, and the first floor is a piloti apartment building with a parking lot) completed in 1994 (see FIG. 24). However, there is a staircase, etc. in the X direction. From the end of August to September 2017, two independent pillars (A2, A3) on the first floor were constructed by the SRF method (1 of paragraph "0194" of this specification). (Refer to the 3rd line from the line). The 2nd to 11th floors are dwelling units, and the 2nd to 10th floors are earthquake-resistant walls.
For measurement, two rows of vertical arrays with instruments installed near the B2 and B3 pillars on each floor, and three instruments each placed near B1, A2 (see Fig. 25) and B3 on the first floor and rooftop. This is a three-point plane observation. Before reinforcement, it was reinforced with 4 instruments on August 25, 2017, and after reinforcement, it was carried out with 12 units on December 19, 2017. In addition, I did not enter the second floor near B2. The first floor plan view of FIG. 26 shows the reinforced pillar positions and instrument arrangements.

2) Measurement result FIG. 27 shows the locus of the fine movement displacement of the B3 vertical array after reinforcement in two horizontal directions for each floor, and the measurement for 6 minutes is divided into 3 parts for 2 minutes each. It can be seen that the amplification is from the first floor to the upper floors, and that each point is almost in a circular motion.

Table 41 shows the energy transfer coefficient of the B2 vertical array and the roof surface, and Table 42 shows the energy transfer coefficient (ratio of the fine movement displacement RMS of the first floor and that floor) and the rate of change before and after reinforcement. The column described as a surface in Table 41 is the energy transfer coefficient related to the rotation of the roof surface around the coordinate axes. After reinforcement, the circumference of the X-axis is reduced to about 1/10, and the circumference of the Y-axis is reduced to about 1/30. The columns below RF in Tables 41 and 42 show the energy transfer coefficient of translational motion and the ratio before and after reinforcement, but both B2 and B3 decrease significantly toward the upper floors. These show the stable effect of the vibration mode by winding two independent pillars (A2, A3) of the piloti part on the first floor, especially the pillar A2 on the lower floor wall, by the SRF method.

Further, FIG. 27 shows the movement of the roof surface before reinforcement and FIG. 28 shows the movement of the roof surface after reinforcement by inputting displacement data (XYZ3 components) by a fine motion meter installed at three locations on the roof surface into the structural analysis result visualization software AVS to visualize it. It depicts a moment of what was (animated). Looking at the animation, it can be seen that before the reinforcement, the roof surface vibrates greatly up, down, left and right, but after the reinforcement, it vibrates in a substantially horizontal plane. This clearly shows that the energy transfer coefficients around the X-axis and Y-axis, which are indicated as faces in Table 1.3.9.1, have decreased to 11% and 3% before and after reinforcement, respectively. is there.

Tables 43 and 44 show the measured values of the layer shear force distribution coefficient (Ai) after reinforcement, the central period (Tc) of the tremor displacement, and the calculated values based on the primary natural period (T) seismic standard (paragraphs of the present specification. 0038 ”to“ 0058 ”). The measured values of A ₁ are almost the same up to the 5th floor, but the upper floors are clearly smaller than the calculated values and the amplification of the seismic motion is small, that is, the vibration mode peculiar to the piloti structure. .. The central period is slightly different between the lower floors and the rooftop, but on the upper floors, both B2 and B3 are almost constant, which is close to the calculated value.

Table 45 shows the measured values of the layer shear force coefficient ( _{Cui1 km} ) of the first layer when the retained horizontal strength near B3 is reached (Formula 27). From the 2nd floor to the 10th floor, the value in the Y direction is larger than that in the X direction, which reflects that the two types of doorway walls on the 2nd to 10th floors are earthquake-resistant walls. The 4th and 5th floors are lower than the other floors. It is said that the construction of this building was interrupted due to heavy rain during the concrete placement work on the 4th and 5th floors, and it was once withdrawn and restarted after about a week. It is probable that this heavy rain and interruption deteriorated the quality of concrete and caused a decrease in the horizontal strength of the concrete.

Table 46 and Table 47, paragraph "0119" of the present specification - "0172" description, and the speed corresponding value of the expected value of the historic absorbed energy led by the contents _{(V mik)} and the degree of damage _{(I dik)} Is shown. The nature of the input seismic motion is assumed to be the strong motion duration s ₀ = 7 sec, the maximum velocity V _max = 0.8 m / sect, and the maximum acceleration V _max = 4.0 m / sec ² as the assumed values of the current seismic standard. In addition, considering that it is a new earthquake-resistant standard building, the toughness index _Fuik = 3.0 is set for each floor and each direction. Incidentally, the limit for the number of repetitions, the second floor above, and N _{ik =} 15 considering that it is a pillar of SRC, first floor N _ik Experiments for confirming the effect of the winding freshly reinforcement by SRF method = It was set to 45.

In Tables 46 and 47, the input seismic motion is represented by the values representing the recent seismic environment, such as strong motion duration s ₀ = sec, maximum velocity V _max = 1.2 m / sec, and maximum acceleration A _max = 10 m / sec ^2. (See Table 19). The toughness index and the limit number of repetitions are as described above.

Looking at the calculation results of the historical absorption energy in Table 46, it was found that the seismic motion assumed by the current standard was hardly absorbed in the Y direction (it did not reach the yield displacement). However, in the X direction, the result is that the 4th, 5th and top floors, which are suspected of having poor concrete construction, surrender. In addition, for the seismic motions that represent the recent seismic environment in Table 48, a large amount of absorbed energy is generated except for the middle floor in the Y direction near B3.

The degree of damage in Tables 47 and 49 indicates whether the energy absorbed by each layer falls within the damage limit, but for the seismic motion assumed by the current standard, the limit value (1) in both XY directions in the vicinity of B2 and B3. The result is that it falls below 0.0). In this sense, it can be said that it conforms to the current standard (new earthquake resistance standard). However, the results show that the 4th and 5th floors, where poor concrete construction is suspected, and the top floor are almost at the limit. On the other hand, with respect to the seismic motion representative of the recent seismic environment in Table 49, in the Y direction near B3, except for the 4th and 5th floors, it falls within the limit, but in the X direction, it causes great damage. In addition, this building has a piloti structure, and it is calculated in Table 48 that a large amount of historical ball energy is generated on the first floor, but even so, the first floor and directly above it are reinforced by winding columns by the SRF method. As for the second floor, the result was almost within the limit value. As for other floors, it is a result that consideration should be given to reducing damage by taking measures such as the winding method.

Although tentatively determined in the above example, the limit number of repetitions and the toughness index of each member can be determined from the load displacement history obtained from the repeated loading experiment on the same type of member and the observation of the degree of damage. In addition, the maximum acceleration, velocity, displacement, and duration of strong ground motion can be determined by comprehensively observing the ground motion.

As shown above, the degree of damage of the present invention is the degree of damage to the structure according to the level of seismic motion and the effect of countermeasures against it, various transmission rates measured by microtremor observation of the structure, and the limit number of repetitions. Can be quantitatively shown using the toughness index. It contributes to the rationalization of seismic design.

Hereinafter, an example of applying the method of the present invention to a block wall will be described.

1. 1. Installation FIG. 29 is a schematic diagram showing the arrangement relationship between the block wall, the foundation and the ground and the microtremor, and the microtremor 1 is horizontally placed on the top 17 of the block wall 16, the foundation 18, or the ground surface 20 near the foundation 18. Install. When the fine movement meter 1 is installed on the top 17 of the block wall 16, the foot 1a of the fine movement meter 1 is placed on the center line of the top 17 of the block wall 16. When installing on the top 17 and the surrounding ground 21, and when the friction on the foundation 18 is large, an iron plate is used.

2. 2. Measurement Simultaneous measurement is performed on the top 17 and the foundation 18 for about 6 minutes. The data will be analyzed using free kick and Excel for fine movement diagnosis as in the case of building diagnosis. At this time, the floor height is the height of the block wall 16 (the difference between the z-coordinates of the tremor 1 at the top 17 and the tremor 1 at the foundation 18 or the surrounding ground 21) H, and the weight supported by the layer is zero.
The calculations are the velocity, displacement calculation, RMS, central period, and transfer coefficient of each time history. The inter-story displacement or the absolute displacement of the top is used as the time history d (t) of interest, and the measurement point of the foundation 17 or the surrounding ground 21 (see No. 1 in FIG. 29) is used as the reference point, and the transmission coefficient ( _hdk ) with this is used. ) Is calculated.

3. 3. Diagnosis The relative displacement or absolute displacement of the top 23 when the reference point displacement x _Gkmax for a large earthquake assumed by the diagnostic criteria is 2.5 cm is predicted by the following equation (yellow main equation 1.4.8).

However, if d (t) = y ₂ (t) -y ₁ (t) and h _dk = RMS [d (t)] / RMS [y ₁ (t)] in the above equation, the relative displacement is predicted. Will be done.

Further, if d (t) = y ₂ (t) and h _dk = RMS [d (t)] / RMS [y ₁ (t)], the absolute displacement is predicted.

Here, d (t), y ₂ (t), and y ₁ (t) are the relative displacements of the top 23 and the reference point, the absolute displacement of the top 23, and the absolute displacement of the reference point in the y direction (block wall 22). (Orthogonal direction) component.

The fall risk ( _Itbw ) of the block wall 15 is calculated from the expected value of the relative displacement between the top 16 and the foundation 17 at the time of an earthquake calculated by the formula 50, or the absolute displacement of the top 16.

If the average value of the fall limit slope is D / H, the following equation is obtained.

However, D [cm] is the width of the block wall 15 (see FIG. 29), and E [d _Gkmax ] is the absolute displacement or relative displacement of the top 16 of the block wall 15 with respect to a large earthquake assumed by the seismic diagnostic criteria. The expected value, a (see Table 50), is the displacement of the top of the fall limit when the fall limit inclination is D / H.

Next, a specific example of fine movement measurement in which the method of the present invention is applied to a block wall will be described below.

The specifications are as follows.
Location: Hirakata City, Osaka Prefecture A certain condominium block wall structure: CB structure Thickness: 150 [mm]
Extension: ~ 15000 ~ [mm]
Height: 1870 [mm] (The height from the reference measuring device to the top is 1790 [mm].
Block size: (thickness x extension x height) 150 [mm] x 390 [mm] x 200 [mm]
Holding wall: None Uses 4 fine movement measuring devices

30 (a) to 30 (c) show the actual measurement situation for each measurement point, of which (a) shows the situation of measurement point 1 and (b) shows the situation of measurement point 2. c) shows the situation of the measurement point 3, respectively. Further, FIG. 31 is an explanatory diagram schematically showing the arrangement state of the measuring device (microtremor) when the block wall is viewed from above in correspondence with FIG. 30.

Regarding the fall risk of the block wall, the fall risk was calculated by the formula 51. The results are shown in Table 51.

According to Table 51, the fall risk was less than 1.0, and it was determined that the fall risk was not great under the seismic motion (maximum displacement 2.5 cm) assumed by the seismic diagnostic criteria. However, there is a risk of falling if the ground motion exceeds this (for example, recent ground motion).

About the role of tremor diagnosis The method of assuming that the action of an earthquake is an inertial force proportional to the ground motion acceleration (inertial force approximation) is based on the current seismic design regardless of the old and new seismic standards, dynamic and static calculations. It is the basic principle. This, coupled with the development of numerical calculation methods typified by the finite element method and digital computers, has created structures of scale, shape, and materials that have never existed on the ground from the latter half of the 1960s to the present, including Japan. It became the driving force for construction one after another in the seismic zone areas around the world.
Seismic calculations have become so complicated that structural design cannot be done without dedicated software because the new seismic standards stipulate that the collapse process of structures should be tracked numerically. Even experts cannot physically grasp structural seismic indicators, retained horizontal strength, or the calculation process of dynamic analysis. The current situation is that we have no choice but to believe in the numerical values that computers give us. On the other hand, from the end of the 20th century to this century, seismic activity became more active, and both the magnitude and duration of the observed seismic motion were several times to one of the assumptions of the current standards set based on seismic observations up to the 1970s. It is an order of magnitude higher.

Inertial force approximation does not hold at recent ground motion levels where ground motion acceleration exceeds 1 G. The irrationality of designing the structure / ground system for three-dimensional motion separately in the x and y directions also stands out. In the first place, the spatiotemporal scale of a large earthquake is incomparable to the scale of individual structures. If we try to capture the seismic motion of a large earthquake on the scale of a structure, it will be extremely random. As for the phenomenon caused by a big earthquake, the result changes greatly discontinuously even if the conditions change a little. This is called a statistical phenomenon. It is not rational in the input seismic motion, nor in the assumptions and models of the calculation, to construct a structure of a scale or type that did not exist before based on the calculation by the method of the current standard.

Research on modern seismic structures started in Japan in the wake of the 1891 Nobi earthquake, coupled with the development and improvement of design and construction technology for reinforced concrete materials, survived the Great Kanto Earthquake of 1923 and moved to Tokyo by the 1960s. It created a profound landscape based on medium- and low-rise RC buildings in major cities such as the one. However, with the abolition of height restrictions in 1963, the 1964 Tokyo Olympics, the high economic growth policy, and the rapid spread of the concrete pump pumping method, the former building was demolished, and overcrowding and high-rise buildings rapidly progressed. There is.

In the area of the Great Hanshin-Awaji Earthquake of 1995 with a seismic intensity of 7, about half of the middle- and low-rise RC buildings are undamaged except for piloti, even if the earthquake motion exceeds the assumption of the current standard more than three times. Yes, only a few percent have collapsed. The civil engineering structures such as the Shinkansen viaduct and highways collapsed, but they were damaged several times as much as expected in the design, and the damage was concentrated in places such as the old river channel that were greatly affected by the ground. It is said that it was natural to do it. The same applies to the 2011 Great East Japan Earthquake. Even with the old standards, only a few buildings collapsed due to earthquake motion. Of the 98 medium- and low-rise RC public buildings with an Is value of 0.3 or less that received an earthquake with a seismic intensity of 5 or higher, none collapsed, and 97 buildings continued to be used with almost no damage. On the other hand, seismic retrofitted school buildings and condominiums became unusable, and were demolished or forced to undergo large-scale repairs. In addition, the Tohoku Shinkansen had already undergone seismic reinforcement using iron plates on the piers, but after the earthquake, it was cut off due to the destruction of beams and superstructures such as overhead lines, and it took more than 50 days to restore. ing.

The need for a drastic revision of the current seismic standards is stated in the diagnostic criteria mentioned above. Here, we describe the features of microtremor diagnosis and the role that microtremor diagnosis plays in performing rational seismic design / supervision and reinforcement work.

(1) Response calculation The performance required of a structure during an earthquake is that there is little damage and that it can be used continuously. At recent seismic motion levels where the ground motion acceleration exceeds 1 G, it is not only physically difficult to track after the structure has become non-linear using indicators such as possessed horizontal strength, but also continuity of use. From the viewpoint of ensuring the above, a structure that does not cause non-linearity itself, that is, a building with high strength (high hurdle for non-linearity) as described in the diagnostic criteria is desired.
What can be understood from the response calculation is the vibration mode, maximum acceleration, velocity, displacement, historical absorption energy, etc. when the structural ground system responds linearly to a specific seismic motion or a general seismic motion. The fine movement diagnosis can directly obtain the information necessary for the calculation within the elastic range. It is also easy to compare calculation and actual measurement.

(2) Assumption of seismic motion The action of an earthquake is a proximity action. It is rational to determine the assumed ground motion (seismic motion used for calculation) based on the actual phenomenon that it is transmitted from the epicenter to the surrounding ground, from the surrounding ground to the foundation, from the foundation to the pillars on the first floor, and from the bottom to the top. Is the target. As is done by the current building standards, the method of predetermining the response acceleration or response spectrum of a structure is not only unreasonable, but also causes the structure to generate excessive seismic force and collapse or be seriously damaged. There is a risk. Furthermore, it would be overwhelming to numerically synthesize seismic motions that match the response spectrum and perform time history response analysis.

As a place to define the assumed seismic motion, there is a method of using it as an engineering foundation surface, which is used in the calculation of limit strength. However, the ground motion actually received by the structure is affected not only by the ground motion of the engineering base directly underneath, but also by a wide range of base surfaces that spread three-dimensionally. Calculations based on actual phenomena, that is, three-dimensional ground vibration analysis calculations, are almost impossible. Instead of this, if one-dimensional overlapping reflection is calculated, the difference between the seismic motion actually input to the structure and the calculated seismic motion must be extremely large.

In the fine movement diagnosis, the input vibration is given at the foundation of the structure. The maximum acceleration, maximum velocity, maximum displacement, and strong motion duration are used as the properties of the assumed ground motion. However, even if a specific numerical value is determined for the magnitude of the assumed ground motion, it will be the expected value (average value). The actual ground motion will be a large variation with respect to this value.

(3) Performance evaluation In recent seismic motions where the ground motion acceleration exceeds 1 G and the duration is several minutes or more, it is inevitable that visible displacements occur from wooden structures to super high rises, and many repetitions occur. An evaluation index that clearly incorporates the occurrence of displacement is needed. Furthermore, it is necessary to evaluate the performance using a set of indexes related to individual members and parts, instead of totaling the indexes for each layer of the structure.
In tremor diagnosis, the degree of damage is defined and used as an index for directly evaluating the continuity of use. This is called a seismic collection performance index.

(4) Rational seismic structures At recent seismic motion levels, structures that exhibit a total collapse shape, as the current standards assume, are inevitably collapsed in calculation, and continuity of use is undesired. .. It is rational to have a structure in which the part that is greatly deformed and vibrated to absorb the energy of seismic motion and the part that is contained within the damage limit are planned in advance.
In a well-formed RC structure, the stigma and pedestal of each column serve as bending hinges, causing overall deformation and movement. In the eccentric one, the piloti, the stigma and pedestal of the part with few walls operate, and the piloti floor and the part shaken by the eccentric vibrate greatly and absorb energy, so that the deformation of other floors and parts is suppressed to a small size. Can be done.
In RC structures, the rigidity of the structural skeleton is sufficiently higher than that of the surrounding ground unless it is located in rock, so in addition to the above-mentioned vibrating part of the skeleton, energy absorption by the boundary (foundation) between the surrounding ground and the skeleton is planned. I want to think about what to do. It is effective to incorporate the relative motion of the foundation and the surrounding ground into the design. In a wooden structure, the deformation and energy absorption capacity of each joint and nailing part is large, so the joint and nailing part have three-dimensional mobility and resilience. In addition, we would like to specifically reflect the reduction of seismic action due to the lifting of the foundation from the foundation in the design.
By calculating the cumulative strength index and damage degree of each part of the structure and visualizing the natural vibration mode for the assumed seismic motion of the current standard by microtremor diagnosis, the antinodes and nodes of vibration can be extracted, and the essential members and parts and By reinforcing the joints to give them energy absorption capacity, it is possible to create a structure that has the kinetic capacity and energy absorption capacity to withstand a large earthquake. The SRF method is effective for the above reinforcement.

(5) Confirmation inspection at the time of new construction and inspection of structural repair work After the structure is completed or after the repair work is completed, a fine movement diagnosis is carried out, and the vibration mode, vibration cycle ( _Tm ), and layer shear force distribution are performed. coefficient _{(a im),} response ratio _{(R amk,} R _vmk), the cumulative strength indicator _{(C T} S _{D) m,} measured damage degree _{(I dm),} from the design calculations, the validity of calculation and construction Can be used as a basis for deciding to add countermeasures as necessary. In addition to calculating each of the above indicators for the entire structure, the vibration characteristics of that part can also be grasped by measuring the vertical array installed in that part.
At present, the inspectors visually confirm the consistency with the drawings in the intermediate inspection and confirmation inspection of the new construction. The same applies to seismic repairs. The fine movement diagnosis can add an objective numerical value to the judgment index of the inspector.

(6) Periodic soundness diagnosis A microtremor diagnosis is performed regularly, each index in the preceding paragraph is measured, and if deterioration of the structure is observed, it is used as a judgment material for repair. In addition, it can be used as a material for confirming the repair effect by performing a fine movement diagnosis again after the repair.

(7) Seismic diagnosis and seismic repair design of existing structures We carry out microtremor diagnosis on existing structures constructed according to the current or old seismic standards, evaluate seismic performance, and design countermeasures as necessary.・ Use as materials for construction. In addition, it can be used as a material for quantitatively confirming the reinforcement effect by measuring and diagnosing before and after reinforcement.
Currently, seismic diagnosis is carried out for a period of several months and at a cost of several million yen or more than 10 million yen. This is because the calculations are complex and require a high degree of expertise. If the diagnostic calculation is simplified and the judgment is made in combination with the index obtained by the fine movement diagnosis, the cost and time can be significantly reduced.

(8) Analysis of damage / no damage cases In the future, if a large number of actual measurement cases are accumulated and correlation analysis with actual damage / no damage in an actual earthquake is performed, the ratio of calculation to judgment by the diagnostician will be minimized. , It is expected that it will be possible to perform repair design such as seismic diagnosis based on the results of fine movement diagnosis and extraction of repaired parts. Furthermore, it will be possible to increase the role of microtremor diagnosis at the time of new construction, after renovation, and in regular inspections, and narrow down calculations and judgments to the required range.

Regarding the issues of seismic standards and solutions using the SRF method (bandage reinforcement), a paper entitled Seismic Reform was published in April 2017. We hope that along with microtremor diagnosis, it will help streamline seismic design and reduce the financial burden and risk of earthquakes.

As is clear from the explanations detailed above, according to the present invention, the cumulative strength index and the expected value of the structural seismic index used in the diagnosis and seismic repair design of the existing existing structure, and the current new construction Define the expected value of the distribution coefficient of the layer shelter force used in the design in the height direction and the degree of damage to directly evaluate the continuity of use of the structure, and obtain the expected value directly from the measured values of microtremors. By doing so, it is possible to measure the seismic sentiment, strength, degree of damage, etc. of each floor part (zone) by observing each part of the structure with a vertical array, resulting in the soundness and safety of the structure. Not only far more detailed seismic design and reinforcement, but also seismic resistance evaluation according to individual vibration characteristics, seismic design and continuity of use of structures (seismic reinforcement work) compared to the conventional method of directly applying external force to the object. The most important target performance for implementation) can be evaluated directly, inexpensively and quickly.

That is, according to the present invention, by using the above indicators, seismic diagnosis can be performed much cheaper and faster than the current seismic diagnosis after new construction, repair work, and regular diagnosis. It will be possible to carry out rational seismic retrofitting design and seismic design of new structures.

1 Microtremor 1a Foot 2 Analyzer 10 Structure 10a, 10b, 10c Layer boundary surface 11 RC hospital building 12 1st floor 13 2nd floor 14 3rd floor 15 4th floor 16 block wall 17 Top 18 Foundation 20 Ground surface 21 Peripheral ground

Claims (11)

In the method of evaluating the performance of structures by constant microtremor observation
Simultaneous tremor time history is constantly observed at multiple observation points in the structure, and the squared mean square root (RMS) of these time histories is used to calculate the estimated value of the index used for seismic design of the structure. , Diagnosis and evaluation of structures based on constant tremors of structures, characterized in that seismic performance of the structures is evaluated based on the observations, using the ratio of this value to the value of the index used at the time of design. Method. Claim that the continuous fine movement time history is divided, a plurality of partial time histories are extracted, the expected value of the index is calculated for each partial time history, and the sample average is used as the estimated value of the index. The method for diagnosing and evaluating a structure based on the constant tremor of the structure according to 1. The method for diagnosing and evaluating a structure based on the constant tremor of the structure according to claim 2, wherein the duration of the partial time history is 1 to 2 minutes. The above observations are made after the new construction of the structure, before and after the repair work, and at the time of regular diagnosis, and by comparing the estimated values at each observation point with each other, the seismic performance of the structure and the risk of collapse in the event of a large earthquake The method for diagnosing and evaluating a structure based on the constant tremor of the structure according to any one of claims 1 to 3, wherein at least one of the change with time and the change before and after the repair work is diagnosed and evaluated. The index is a diagnostic evaluation method for a structure based on the constant tremor of the structure according to any one of claims 1 to 4, which is a distribution coefficient in the height direction of the layer shear force specified in the current standard. The index is a method for diagnosing and evaluating a structure based on the constant tremor of the structure according to any one of claims 1 to 4, which is the possessed horizontal strength specified in the current standard. The index is a method for diagnosing and evaluating a structure based on the constant tremor of the structure according to any one of claims 1 to 4, which is a base shear coefficient defined in the current standard. The index is a diagnostic evaluation method for a structure based on the constant tremor of the structure according to any one of claims 1 to 4, which is an acceleration response magnification specified in the current standard. The index is a method for diagnosing and evaluating a structure based on the constant tremor of the structure according to any one of claims 1 to 4, which is the product of the cumulative strength index and the shape index defined in the current standard. The index is a method for diagnosing and evaluating a structure based on the constant tremor of the structure according to any one of claims 1 to 4, which is the degree of damage. The index is a method for diagnosing and evaluating a structure based on the constant tremor of the structure according to any one of claims 1 to 4, which is a fall risk.